Reciprocating high-pressure pumps, such as those for oil field use, are usually designed in two sections, the (proximal) power section (herein “power end”) and the (distal) fluid section (herein “fluid end”). The power end comprises a crankshaft, reduction gears, bearings, connecting rods, crossheads, crosshead extension rods, etc. The fluid end comprises a housing which in turn comprises one or more functional units, each functional unit comprising a suction valve, a discharge valve, and a plunger or piston bore in which a reciprocating plunger or piston alternately produces suction strokes and pressure strokes. See, e.g., U.S. Pat. No. 7,513,759 B1, incorporated herein by reference.
Suction valves of high pressure oil field pumps experience wide pressure variations between a suction stroke, when the valve opens, and a pressure stroke, when the valve closes. For example, during a pressure stroke a valve body and seal assembly may be driven toward contact with its corresponding valve seat with total valve closing force that typically varies from about 50,000 to 150,000 pounds applied to the proximal surface of the valve body. Actual valve closure impact occurs with metal-to-metal contact between the valve body's valve seat interface and the valve seat itself. Such impact stops a conventional valve body abruptly, together with a proximal mass of moving pressurized fluid which is in contact with the valve body. The kinetic energy of the moving valve body and pressurized fluid is thus nearly instantly converted to a high-amplitude closing energy impulse of short duration. The sharply rising impulse of closing energy is quickly transmitted to the valve seat and adjacent areas of the pump housing in the form of characteristically broadband vibration which induces damaging resonances within the valve and adjacent pump housing structures. See, e.g., U.S. Pat. No. 5,979,242, incorporated herein by reference. Rapid valve wear and the early emergence of structurally significant fatigue cracks in the pump housing near the valve seat are commonly seen under these conditions.
Proposed designs which could alleviate a subset of the problems associated with high-amplitude closing energy impulses have included hollow (and thus lighter) valve bodies comprising one or a plurality of interior cavities. See, e.g., U.S. Pat. No. 7,222,837 B1, incorporated herein by reference, and referred to hereinafter as the '837 patent. Notwithstanding the somewhat lower closing energy impulse amplitudes theoretically associated with such valve bodies, they nevertheless have not found wide industry acceptance. A more effective valve body design for reducing pump damage due to closing energy impulse-related vibration is thus needed.